Amazake

Amasake is a sweetener known for a long time in East Asia. It is produced by enzymatic fermentation of rice, or more rarely of other cereals (Kōji). The ferment used for this purpose is koji, the same applied to make rice miso or sake. The grain of rice is entirely pre-digested by Saccharomyces and split into simpler sugars, producing the most modulated and less invasive among sweeteners. It contains less than 40% of maltose. The best amazake is produced with sweet rice.

The basic recipe for Amazake has been the same for hundreds of years: Kōji is added cold cooked whole grain rice and then warmed up to 50-60 C. The enzymes of the mold will break down the starch of the rice into sugar so that the mixture becomes gradually sweet. The process is usually complete after 6 to 12 hours.  If the grains or containers were contaminated with lactic acid bacteria, a competitive fermentation could occur producing lactic acid.  Because all enzymatic reactions are temperature sensitive, it is essential to work in the recommended temperature range.  If the temperature is too high, the enzymes of the koji are not too active resulting in a slowdown of the saccharification, and thus the sweetness is not too high. If the temperature is too low, the lactic acid fermentation will dominate by growing more bacteria resulting in a sour product.
Usually, a minimal amount of alcohol is formed due to the contamination of the grains by natural yeast.

Amazake can be used as a dessert, snack, natural sweetener, baby food or salad dressing. The traditional drink is prepared by dilution with water, heated to boiling point and often decorated with some finely grated ginger.